1. Field of the Invention
The present invention relates generally to electronic item identification systems and more particularly, to a radio frequency (RF) identification tag and method for identifying an item to or with which the tag is attached or associated, respectively, wherein each tag includes a plurality of circuits having a capacitance.
2. Background of the Related Art
Conventionally, transportation of goods is conducted by utilizing railways, trucks, ships, airplanes and so on. In recent years, however, transportation of light-weight parcels by small trucks or the like, called Takuhaibin, have become very popular because of its low cost. In this type of transportation, a forwarding agent collects and delivers parcels to destinations in a short period of time. This transportation is known by its simple procedure and fast delivery of parcels.
In such transportation, parcels are attached with a label on which a sender, a destination and so on are filled in. A delivery man looks at the labels on the parcels and thereby checks the destinations and conducts sorting out of the parcels. Recently, checking of destinations and sorting out of the parcels have also been conducted in the following manners: in one method, destinations are coded, and sorting out of the parcels are conducted using the coded destinations. In another method, a delivery man carries with him or her a bar code system, and parcels carry on them a label on which bar codes representing a sender, destination and so on are printed.
However, in this transportation method, parcels are often delivered to a wrong destination or lost before they reach the destinations. Such accidents cost a forwarding agent substantial sums of money for investigation and compensation.
These accidents may be decreased by reinforcing visual checking of parcels. However, reinforcement of visual checking of parcels increases cost and prolongs the time for delivery. In any way, it requires manpower and limits reliability. Currently, electronic item identification systems are in widespread use today to identify a variety of items. A first type of electronic item identification system commonly used in industry is one in which bar code labels are used to identify items. These types of electronic item identification systems are typically used by supermarkets, distributors, shipping services and clothing retailers to scan the bar code labels for quick retrieval of an item's price or other information.
The way conventional bar code identification systems work is as follows. Bar codes labels are made up of a series of lines of varying widths or thicknesses to establish a code which can be read by a scanner. A bar code label is usually read by a laser scanner. The data from the scanner is electronically fed to a receiver which determines the identification code or number associated with the bar code label. The identification code or number is then sent to a central processing unit or computer where each code or number is matched to data stored on a master list such as item price or other information. The central processing unit or computer then electronically sends the stored data associated with the identification code or number to the cash register or other tabulator to arrive at a final total or tabulated result.
Another system of electronic item identification uses radio frequency (RF) identification tags to identify items. Radio frequency (RF) identification tags can be used to identify a variety of items to which the tags are attached or otherwise associated. In particular, radio frequency (RF) identification tags are currently used to identify passengers, luggage, library books, inventory items and other articles. Radio frequency (RF) identification tags will allow electronic identification of people or objects, moving or stationary, at distances of several feet.
Prior art devices short out capacitors during interrogation and thus the circuit can never be restored to its original frequency to be read over again. It is therefore desirable to develop an electronic item identification system in which the radio frequency (RF) identification tag can be read any number of times while still generating the same binary number as was read the first time and in this manner the tag can be reused.
It is also desirable to develop an electronic item identification system in which a radio frequency (RF) identification tag has numerous circuits made up of capacitor/inductor coil pairs at evenly spaced intervals on the surface of the tag so that the presence or absence of a circuit or the circuit's functionability could be programmed at the point of use with inexpensive equipment.